Diagnosis Hydroid with an oral whorl of up to ten capitate tentacles, without aboral filiform tentacles; medusae buds carried in clusters on short blastostyles (gonostyle) or singly at base of hydranth.
Medusae adapted for crawling, unable to swim; umbrella with or without continuous ring of nematocysts along margin; with four or more simple and short radial canals; manubrium with broad base, conical, with simple circular mouth; with or without brood-chamber above base of stomach; gonads either on manubrium, or in brood-chamber from where they can also extend to the epidermis of the subumbrella; 6-14 bifurcated marginal tentacles, one upper branch with a single terminal nematocyst knob, one lower branch[details]